The 27 states challenging Obama’s Clean Power Plan in court say the lower emissions levels it would impose are an undue burden. But most are likely to hit them anyway.

Already, Arkansas, North Carolina, Oklahoma and South Dakota appear to be meeting the CPP’s early targets. And changes in the power market, along with policies favoring clean generation, are propelling most of the rest toward timely compliance, according to researchers, power producers and officials, as well as government filings reviewed by Reuters.

“We are seeing reductions earlier than we ever expected,” U.S. Environmental Protection Agency Administrator Gina McCarthy said in an interview. “It’s a great sign that the market has already shifted and people are invested in the newer technologies, even while we are in litigation.”